I'd say starting a company to make something people want in order to sell it for money is still relevant. It's just that you're looking at working quietly, humbly, but perseverantly for the next 25 years, slowly growing the business and balancing the risks and opportunities along the way. You won't be looking for an "exit" because you want to take care of the company you built. That's a very different story from whatever vibe it is that startups acquired after the dotcom boom, i.e. find something that hasn't been done before, scales quickly, and sell the company after a few years for 1000x, and then something.

That never was sustainable, I think, and effectively it became a glorified hiring process for big tech who bought the best toy companies to get to the people behind. And now even big tech figured it's cheaper to just hire the talent directly and not buy their token company for a few million first just to get the guys in.

Not saying a good company with a good idea and execution at the right time couldn't still make it big quick: there always were some lucky ones and there will always be. But the process isn't repeatably stable enough that there's a lot of wasted effort to make a few shooting stars. And everybody seems to be slowly accepting that. Go for it if the opportunity arises but if you spend 10 years trying and trying without the fish biting you're likely better off saving off from a decent salary when those years have passed.